Flexible press fit pins for semiconductor packages and related methods

ABSTRACT

Implementations of pins for semiconductor packages may include: an upper contact portion having a contact surface configured to mechanically and electrically couple with a pin receiver; a lower portion having a vertical stop and at least two curved legs; a horizontal base coupled directly to the at least two curved legs and configured to be soldered to a substrate to mechanically and electrically couple the pin to the substrate, the horizontal base having an upper contact surface, and; a gap between a bottom contact surface of the vertical stop and the upper contact surface of the horizontal base; wherein the at least two curved legs are configured to flex to allow the bottom contact surface of the vertical stop to move toward the upper contact surface of the horizontal base in response to a pressure applied to the pin along a direction collinear with a longest length of the pin toward the upper contact surface, and; wherein the vertical stop is configured to stop movement of the pin when the bottom contact surface contacts the upper contact surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of the earlier U.S.Utility patent application to Yao et al. entitled “Flexible Press FitPins for Semiconductor Packages and Related Methods,” application Ser.No. 15/443,671, filed Feb. 27, 2017, which claimed the priority of theearlier U.S. Utility patent application to Yao et al. entitled “FlexiblePress Fit Pins for Semiconductor Packages and Related Methods,”application Ser. No. 14/703,002, filed May 4, 2015, issued as U.S. Pat.No. 9,620,877 on Apr. 11, 2017, which claimed the benefit of the filingdate of U.S. Provisional Patent application Ser. No. 62/013,322, filedJun. 17, 2014, to Yao et al., entitled “Power Integration Module withPress Fit Pins,” the disclosures of each of which are herebyincorporated entirely herein by reference.

BACKGROUND 1. Technical Field

Aspects of this document relate generally to pins used for semiconductorpackages. Particular aspects of this document relate to pins used forpower semiconductor packages, such as power integrated modules (PIMs).

2. Background

Semiconductor devices are often encased within (or partly within) apackage prior to use. Some packages contain a single die while otherscontain multiple die. The package offers protection to the die and oftenalso includes electrical leads or other components which connect theelectrical contacts of the die with a motherboard, printed circuit board(PCB) or other element. The electrical leads may be in the form of pinswhich are soldered or otherwise coupled with a substrate within a casingand which extend through openings in the casing to mechanically andelectrically couple with pin receivers. The package may also includecomponents configured to dissipate heat.

SUMMARY

Implementations of pins for semiconductor packages may include: an uppercontact portion having a contact surface configured to mechanically andelectrically couple with a pin receiver; a lower portion having avertical stop and at least two curved legs; a horizontal base coupleddirectly to the at least two curved legs and configured to be solderedto a substrate to mechanically and electrically couple the pin to thesubstrate, the horizontal base having an upper contact surface, and; agap between a bottom contact surface of the vertical stop and the uppercontact surface of the horizontal base; wherein the at least two curvedlegs are configured to flex to allow the bottom contact surface of thevertical stop to move toward the upper contact surface of the horizontalbase in response to a pressure applied to the pin along a directioncollinear with a longest length of the pin toward the upper contactsurface, and; wherein the vertical stop is configured to stop movementof the pin when the bottom contact surface contacts the upper contactsurface.

Implementations of pins for semiconductor packages may include one, all,or any of the following:

The vertical stop may be located between the at least two curved legs.

The upper contact portion may include a deformable portion configured todeform along a direction perpendicular with the longest length of thepin in response to inserting the upper contact portion into the pinreceiver.

The pin may include a plurality of stops extending perpendicular to thelongest length of the pin and configured to prevent the pin from movingrelative to a casing of a semiconductor package when the pin is removedfrom the pin receiver.

Each of the at least two curved legs may form an s-shape.

The s-shapes of the at least two curved legs may be parallel to oneanother.

The pin may include a first gap between an upper curve of each of the atleast two curved legs and the vertical stop and a second gap between alower curve of each of the at least two curved legs and the verticalstop, the first gap and the second gap visible when the pin is viewedfrom a perspective wherein one of the at least two curved legs is fullyhid behind another of the at least two curved legs.

Each of the at least two curved legs may include a slanting portionslanting towards the vertical stop along a direction diagonal to a planeof curvature of one of the at least two curved legs.

There may be no gaps visible between the at least two curved legs andthe vertical stop apart from the gap between the bottom contact surfaceof the vertical stop and the upper contact surface of the horizontalbase when the pin is viewed from a perspective fully hiding one of theat least two curved legs behind another of the at least two curved legs.

Implementations of pins for semiconductor packages may include: an uppercontact portion having a contact surface configured to mechanically andelectrically couple with a pin receiver; a lower portion consisting oftwo partially curved legs, and; a horizontal base coupled directly tothe two partially curved legs and configured to be soldered to asubstrate to mechanically and electrically couple the pin to thesubstrate; wherein the two partially curved legs are curved incomplementary opposing directions away from a longest length of the pin,and; wherein the two partially curved legs are configured to deform inthe complementary opposing directions in response to a pressure appliedto the pin along a direction collinear with the longest length of thepin toward the horizontal base.

Implementations of pins for semiconductor packages may include one, all,or any of the following:

Each of the two partially curved legs may terminate in a vertical,non-curved portion coupled directly to the horizontal base.

The pin may have a gap between the two partially curved legs that isvisible when the pin is viewed along a direction wherein the vertical,non-curved portion of one of the two partially curved legs is fullyhidden behind the vertical, non-curved portion of the other of the twopartially curved legs.

The pin may include a plurality of stops extending perpendicular to thelongest length of the pin and configured to prevent the pin from movingrelative to a casing of a semiconductor package when the pin is removedfrom the pin receiver.

The upper contact portion may include a deformable portion configured todeform along a direction perpendicular with the longest length of thepin in response to inserting the upper contact portion into the pinreceiver.

Each of the two partially curved legs may include only a single curvethat is concave relative to the single curve of the other of the twopartially curved legs.

Implementations of pins for semiconductor packages may include: an uppercontact portion having a contact surface configured to mechanically andelectrically couple with a pin receiver; a lower portion bent into anN-shape, wherein a first bend of the N-shape couples a first section ofthe N-shape into a slanted section of the N-shape and a second bendcouples the slanted section of the N-shape to a second section of theN-shape substantially parallel with the first section of the N-shape; ahorizontal base coupled directly to the second section of the N-shape,the horizontal base configured to be soldered to a substrate tomechanically and electrically couple the pin to the substrate, thehorizontal base having an upper contact surface, and; a gap between alower contact surface of the first bend and the upper contact surface ofthe horizontal base; wherein the N-shape is configured to flex to allowthe lower contact surface to move toward the upper contact surface inresponse to a pressure applied to the pin along a direction collinearwith a longest length of the pin toward the upper contact surface, and;wherein the N-shape is configured to stop flexing after the N-shape hasbent sufficiently to allow the lower contact surface to contact theupper contact surface.

Implementations of pins for semiconductor packages may include one, all,or any of the following:

The first section of the N-shape may be collinear with the longestlength of the pin.

The second section of the N-shape may be coupled to the horizontal basethrough a third bend having an angle between 60 and 120 degrees.

The upper contact portion may include a deformable portion configured todeform along a direction perpendicular with the longest length of thepin in response to inserting the upper contact portion into the pinreceiver.

The pin may include a plurality of stops extending perpendicular to thelongest length of the pin and configured to prevent the pin from movingrelative to a casing of a semiconductor package when the pin is removedfrom the pin receiver.

The foregoing and other aspects, features, and advantages will beapparent to those artisans of ordinary skill in the art from theDESCRIPTION and DRAWINGS, and from the CLAIMS.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations will hereinafter be described in conjunction with theappended drawings, where like designations denote like elements, and:

FIG. 1 is a front-side view of an implementation of a flexible press-fitpin;

FIG. 2 is a front-side view of another implementation of a flexiblepress-fit pin;

FIG. 3 is a top-front-side perspective view of another implementation ofa flexible press-fit pin;

FIG. 4 is a front-side view of another implementation of a flexiblepress-fit pin;

FIG. 5 is a side view of the flexible press-fit pin of FIG. 1;

FIG. 6 is a side view of the flexible press-fit pin of FIG. 2;

FIG. 7 is a side view of the flexible press-fit pin of FIG. 3;

FIG. 8 is a side view of the flexible press-fit pin of FIG. 4;

FIG. 9 is a front view of the flexible press-fit pin of FIG. 1;

FIG. 10 is a front view of the flexible press-fit pin of FIG. 2;

FIG. 11 is a front view of the flexible press-fit pin of FIG. 3;

FIG. 12 is a front view of the flexible press-fit pin of FIG. 4;

FIG. 13 is a top-front-side perspective view of a semiconductor packageincluding the flexible press-fit pin of FIG. 1;

FIG. 14 is a cross-section view of the semiconductor package of FIG. 13taken along line A-A;

FIG. 15 is a front perspective view of another implementation of aflexible press-fit pin;

FIG. 16 is a side view of the flexible press-fit pin of FIG. 15;

FIG. 17 is a rear perspective view of the flexible press-fit pin of FIG.15;

FIG. 18 is a rear view of the flexible press-fit pin of FIG. 15; and

FIG. 19 is a front side view of another implementation of a press-fitpin without a gap between the two curved portions.

DESCRIPTION

This disclosure, its aspects and implementations, are not limited to thespecific components, assembly procedures or method elements disclosedherein. Many additional components, assembly procedures and/or methodelements known in the art consistent with the intended flexible pressfit pins for semiconductor packages and related methods will becomeapparent for use with particular implementations from this disclosure.Accordingly, for example, although particular implementations aredisclosed, such implementations and implementing components may compriseany shape, size, style, type, model, version, measurement,concentration, material, quantity, method element, step, and/or the likeas is known in the art for such flexible press fit pins forsemiconductor packages and related methods, and implementing componentsand methods, consistent with the intended operation and methods.

Referring now to FIGS. 1, 5, and 9, in various implementations aflexible press-fit pin (pin) 2 includes a body 4. In the implementationsillustrated, this is a rectangular body 6 having a number of sidesurfaces 8. The pin 2 includes an upper contact portion 12 with contactsurfaces 14 configured to electrically and physically couple with a pinreceiver, such as a pin receiver of a motherboard, a printed circuitboard (PCB), or another electrical component, or the like. The uppercontact portion 12 includes deformable portion 16. A cavity 18 of theupper contact portion 12 provides room for the sidewalls 20 of thedeformable portion to deform inwards when the upper contact portion isinserted into a pin receiver. The pin receiver generally will have adiameter slightly smaller than that of the pin so that the deformationoccurs. This may include plastic deformation, though in implementationsit could be only elastic deformation. The difference in size between theupper contact portion 12 and the pin receiver results in a friction fitbetween the two. Thus, when the upper contact portion of the pin 2 isinserted into a pin receiver, it is secured into place through thecompressive forces between the contact surfaces 14 and the surface(s) ofthe pin receiver.

As shown in FIGS. 13-14, in use the pin will be coupled with a substrate180 and will be in electrical communication with one or more die 190such as through electrical couplers 192 and/or through traces on anupper surface of the substrate. The electrical couplers may be wirebonds194, clips, or other elements. The substrate shown in FIG. 14 is adirect bonded copper (DBC) substrate 182 having a ceramic layer 186sandwiched between a first copper layer 184 and second copper layer 188.Any other type of substrate could be used, however, instead of a DBCsubstrate. In the implementations shown the pin is coupled to thesubstrate with a solder 178, though an electrically conductive adhesiveor other coupling mechanism could be used in other implementations. Inimplementations in which the substrate is a DBC substrate the ceramiclayer may include Al2O3.

The casing 196 at least partially encloses the substrate 180 andincludes openings 198, each of which is sized sufficiently to allow anupper end of a pin 2 to extend therethrough. In other words, eachopening 198 includes a diameter larger than a diameter of the uppercontact portion 12. A number of stops 22 are included on each pin. Inimplementations each pin includes four stops, one on each side surface8. In other implementations there could be fewer stops, such as only twoon opposing side surfaces 8. Each stop 22 is a projection 24. Theprojection 24 could have any closed three-dimensional shape. In theimplementations shown they are cuboidal.

When semiconductor package (package) 202 is coupled with a motherboard,printed circuit board (PCB), or other component (such as by pressing thepins 2 into pin receivers of the motherboard, PCB, or other component),a flexible portion of each pin will flex to some degree, as will bedescribed hereafter. Later, if the package 202 is removed from themotherboard, PCB or other component, the flexible portion will allow thepin to expand upwards so that the stops 22 approach the inner surface200 of the casing 196. When the stops 22 contact the inner surface 200the pin is then mechanically prevented from extending further upwards,which stops the pin from decoupling from the substrate at the solderpoint or other contact location. This may also prevent fracture of thesolder or other connection at the contact location. Package 202 is apower integration module (PIM), though in implementations it could be apackage other than a PIM.

Referring to FIGS. 1, 5, and 9, a lower portion 32 of each pin 2includes a vertical stop 38 between two curved legs 34. Each curved leg34 includes an s-shape 36. The vertical stop 38 includes a bottomcontact surface 40. The lower portion 32 is coupled with a base(horizontal base) 26 which includes a lower contact surface 28configured to be coupled with a substrate, as described above, and anupper contact surface 30. There is a gap 42 between the vertical stopand the base or, in other words, between the bottom contact surface 40of the vertical stop 38 and the upper contact surface 30 of the base 26.When the pin is inserted into a pin receiver, as described previously,the pressure of pushing the pin therein may cause a compressive pressureon the pin along a longest length of the pin, and the curved legs 34 areconfigured to allow the pin to compress along this longest length and toallow some deformation of the pin. This may, by non-limiting example,allow the pin to absorb some of the pressure of installation of themodule onto a motherboard, PCB or the like without imparting all of thepressure onto the substrate below. It may also permit deformation duringthermal power cycling of the semiconductor package. This deformation orflexing may, in some implementations, be fully elastic though, in otherimplementations, it could be plastic deformation.

The vertical stop prevents the pin from flexing downwards (or, in otherwords, compressing along the longest length of the pin) beyond a certaindistance. When the vertical stop 38 contacts the base 26, by the bottomcontact surface 40 of the vertical stop 38 coming into contact with theupper contact surface 30 of the base 26, the curved legs 34 then ceaseflexing or deforming further, so that the pin 2 stops flexing ordeforming downwards (or, in other words, stops compressing along thelongest length of the pin). During operation, the curved legs 34 arethose that carry electrical current between the upper contact portion 12and the base 26 of the pin 2. The vertical stop 38 generally does notcarry current between the upper contact portion 30 and the base 26 ofthe pin 2 because, in general, the gap 42 is present when thesemiconductor package 202 is being used and, further, because there is agap 44 between each curved leg 34 and the vertical stop 38. Each pin 2includes a longest length 10, measured from the lower contact surface 28to the top of the upper contact portion 12.

As seen from FIG. 5, in implementations when the pin 2 is viewed fromthe side (i.e., so that one curved leg is substantially hid, or is fullyhid, behind the other curved leg) there are no gaps visible between thecurved legs 34 and the vertical stop 38 apart from the gap between thebottom contact surface 30 of the vertical stop 38 and the upper contactsurface 30 of the horizontal base 26.

Referring to FIGS. 2, 6, and 10, in various implementations, a flexiblepress fit pin (pin) 46 includes many elements in common with pin 2 andsome different elements. Above the lower portion 50 the pin 46 isidentical or substantially identical to pin 2. The pin 46 has a longestlength 48 measured from a lower contact surface 64 of the base(horizontal base) 62 to the top of the upper contact portion 12 of pin46. The main difference between pin 46 and pin 2 is the lower portion50. Lower portion 50 includes a pair of partially curved legs 52. Eachpartially curved leg 52 includes a curve 54 and terminates in anon-curved portion 56 coupled directly to the horizontal base. Thenon-curved portion 56 in each case is a vertical portion. When the pin46 is viewed from the side, as shown in FIG. 6 (so that the non-curvedportion of one partially curved leg is substantially hid, or is fullyhid, behind the non-curved portion of the other partially curved leg), agap 58 is visible between the two curves 54. Thus the curves are curvedin opposite directions and, therefore, form complementary opposingcurves (curves) 60 curving away from a longest length of the pin 46. Insome implementations, there need not be a gap 58 visible when the pin 46is viewed from the side, but there may be no visible gap or the pins mayvisually overlap when viewed from the side. The partially curved legs 52are configured to deform in complementary opposing directions inresponse to a pressure applied to the pin 46 along a direction collinearwith the longest length of the pin 46 toward the base 62.

When the pin 46 is being inserted into a pin receiver, such that thereis pressure downwards on the pin (or, in other words, a compressiveforce along the longest length of the pin) the complementary opposingcurves 60 are configured to bow outwards, to allow the pin to flex. Thisbowing movement may be purely elastic deformation or it may also includeplastic deformation in some implementations. Pin 46 does not have avertical stop—as seen in FIG. 10, there is a space between the twopartially curved legs instead of the vertical stop that is located inthat place on pin 2 of FIG. 9. In other implementations, a vertical stopcould be included in this space, similar to the vertical stop of pin 2.Both of the partially curved legs 60 are configured to conductelectricity between the upper contact portion and the base 62 of the pin46 and, if a vertical stop were added, the vertical stop would generallynot conduct electricity between the upper contact portion and the baseof the pin, as has been described with respect to pin 2. As can be seen,each of the two partially curved legs 52 includes only a single curvethat is concave relative to the single curve of the other of the twopartially curved legs 52.

Referring to FIGS. 3, 7, and 11, in various implementations, a flexiblepress fit pin (pin) 66 includes many elements in common with pin 2 andsome different elements. Above the lower portion 70 the pin 66 isidentical or substantially identical to pin 2. The pin 66 has a longestlength 68 measured from a lower contact surface 80 of the base(horizontal base) 92 to the top of the upper contact portion 12 of pin66. The main difference between pin 66 and pin 2 is the lower portion70. Lower portion 70 includes, instead of multiple legs, a single leg 72that is bent into an N-shape 76. The N-shape 76 includes a firstsubstantially vertical section 74, a slanted section 84, and a secondsubstantially vertical section 77, forming the N-shape. In variousimplementations, the first substantially vertical section 74 is not justsubstantially vertical, but is fully vertical. In other implementations,the second substantially vertical section 77 is not just substantiallyvertical, but is fully vertical. In particular implementations, thefirst substantially vertical section 74 is parallel with, or issubstantially parallel with (or is in other words collinear with), thelongest length 68 of the pin.

Accordingly, the lower portion 70 includes a first section 82 alignedwith the longest length of the pin. A first bend 78 couples the firstsection 82 with the aforementioned slanted section 84. The first bend 78in the figures is shown as being somewhat rounded, though in otherimplementations it could be more or less rounded and even sharp edged. Alower contact surface 80 of the first bend is configured to act as astop, similar to the vertical stop of pin 2, when it contacts an uppercontact surface 94 of the base 92. Thus, in general, when the pin 66 isin a relaxed configuration, there is a gap 96 present between the uppercontact surface 94 of the base and the lower contact surface of thefirst bend 78. When the pin is being inserted into a pin receiver or inother circumstances wherein there is a downwards pressure on the pin(or, in other words, a compressive force on the pin in a directionsubstantially parallel with the longest length of the pin), the gap 96narrows until, if enough pressure is applied, the lower contact surface80 of the bend contacts the upper contact surface 94 of the base andprevents further downwards flexing (i.e., compression) of the pin. Thusthe N-shape allows the pin some downward flexing (compression) butprevents movement beyond a certain distance. As described with respectto the other pins, this flexing may be fully elastic or, in variousimplementations, it could include plastic deformation.

As can also be seen from FIG. 7, the first section may form an angle ofabout three degrees to about thirty degrees with the slanted sectionthrough the first bend. In various implementations this angle may be anangle of, or of about, seven degrees. The second section may form anangle of about three degrees to about thirty degrees with the slantedsection through the second bend. In particular implementations, thisangle may be an angle of, or of about, seven degrees. The second sectionmay make an angle of about sixty to one hundred and twenty degrees withthe base through the third bend. In particular implementations, thisangle may be, or may be about, ninety degrees. There is a second bend 86that couples the slanted section 84 with the second section 88, andthere is a third bend 90 which couples the second section 88 with thebase 92.

Thus, as has been described and as is illustrated in the drawings, theN-shape 76 is configured to flex to allow the lower contact surface 80of the first bend 78 to move toward the upper contact surface 94 of thebase 92 in response to a pressure applied to the pin 66 along adirection collinear with a longest length of the pin 66 toward the uppercontact surface 94, and the N-shape 76 is further configured to stopflexing after it has bent sufficiently to allow the lower contactsurface 80 of the first bend 78 to contact the upper contact surface 94of the base 92.

Referring to FIGS. 4, 8, and 12, in various implementations a flexiblepress fit pin (pin) 98 includes many elements in common with pin 2 andsome different elements. Above the lower portion 102 the pin 98 isidentical or substantially identical to pin 2. The pin 98 has a longestlength 100 measured from a lower contact surface of base 92 to the topof the upper contact portion 12 of pin 98. The main difference betweenpin 98 and pin 2 is the lower portion 102. Lower portion 102 includes astructure which is somewhat similar, but differs in various respectsfrom the lower portion 32 of pin 2.

Lower portion 102 includes two curved legs 104 and a vertical stop 112.A bottom contact surface 114 of the vertical stop 112 faces an uppercontact surface 94 of the base 92 and, as with the vertical stop of pin2, is configured to prevent further downward flexing (i.e., compression,movement) of the pin 98 once the vertical stop 112 contacts the base 92.Thus, in an unflexed configuration, there is a gap 116 between thevertical stop 112 and the base 92. The curved legs 104 are configured toflex, when a compressive pressure is applied on the pin 98 along thelongest length of the pin 98 (such as during installation of the pin 98into a pin receiver). This flexing may be fully elastic or, inimplementations, may include plastic deformation. The lower portion ofthe pin 98 may also allow the pin to flex (i.e., expand) under a tensilepressure applied on the pin along the longest length of the pin (such asduring removal of the pin from a pin receiver).

Each curved leg 104 includes a curved portion 106 including an uppercurve 108 and a lower curve 110 opposing the upper curve (or, in otherwords, curving in an opposite direction from the upper curve). Whenviewed from the side, as in FIG. 8 (wherein one curved leg issubstantially hid, or is fully hid, behind the other curved leg) thereare a plurality of gaps 122 between the vertical stop and the curvedleg. A gap 118 is seen between the upper curve and the vertical stop anda gap 120 is seen between the lower curve and the vertical stop. Inother implementations these gaps 118, 120 need not be present, thoughconfiguring the legs to have the gaps present may result in desirable orimproved bending or flexing characteristics of the pin.

Referring now to FIGS. 15-18, in implementations a flexible press fitpin (pin) 124 includes many elements in common with pin 2 and somedifferent elements. Pin 124 includes a longest length 126 measured froma lower contact surface 152 of a base (horizontal base) 150 to a topmostsurface of a tip 136 of an upper contact portion 134. The pin 124includes a body 128 which in the implementation shown is a rectangularbody 130 having a number of side surfaces 132. The upper contact portion134 includes a deformable portion 140 including a cavity 142 defined bysidewalls 144 and contact surfaces 138 on the outer surfaces of thesidewalls. Functionally, the upper contact portion 134 and deformableportion 140 operates identically to, or similarly to, upper contactportion 12 and deformable portion 16 of pin 2.

Pin 124 also includes one or more stops 146. These operate similarly oridentically to stops 22 of pin 2, and they are formed of projections148, though they have a slightly different shape than stops 22, as canbe seen. Instead of being cuboidal in shape, they are trapezoidal, andindeed the stops of any pins disclosed herein may have any closedthree-dimensional shape so long as they are configured to function asdescribed above with respect to the stops 22 of pin 2. As is seen in thefigures, in some implementations, there are only two stops 146, onopposite sides of the pin 124. While three or four stops could beincluded in other implementations, having only two stops in theconfiguration shown in the drawings may provide for easier manufacturingas, in implementations, the entire pin 124 may then be stamped from asingle flat sheet of metal and bent/pressed into place (instead of, forinstance, beginning with a sheet of metal which has projections in it tobegin with or otherwise forming or attaching the additional stops).

The lower portion 156 of pin 124 includes a vertical stop 168 locatedbetween two curved legs 158. The vertical stop 168 includes a bottomcontact surface 170 facing the upper contact surface 154 of base 150.Thus, in an unflexed configuration, there is a gap 172 between thevertical stop 168 and the base 150. The curved legs 158 flex, when thereis a downward pressure applied on the pin, until the vertical stopcontacts the base, similar to what has been described with respect toother pins herein. This flexing may be fully elastic or, inimplementations, may include plastic deformation.

When viewed from the side, as in FIG. 16 (wherein one curved leg issubstantially hid, or is fully hid, behind the other curved leg), thecurvature 160 of each curved leg 158 includes an upper curve 162 and alower curve 164. The lower curve is curved opposite the curvature of theupper curve. A gap 174 is present between the vertical stop 168 and theupper curve 162, and a gap 176 is present between the vertical stop andthe lower curve 164. When viewed from the back as in FIG. 18 (or fromthe front), a slanting portion 166 is shown at the bottom of each curvedleg 158. Each slanting portion 166 couples one of the curved legs withthe base 150. Each slanting portion 166 slants downwards and inwardstowards the vertical stop along a direction that is diagonal to a planeof curvature of one of the at least two curved legs 158 (the plane ofcurvature is a plane in which a majority of the curvature of the curvedleg may reside, and is parallel with a longest length of the pin).

In other implementations the curved leg could exclude the gaps betweenthe curved legs and the vertical stop and/or could exclude the slantingportions, but in various implementations these characteristics may helpto achieve desired flexing characteristics of pin 124.

The vertical stop 168, as with other vertical stops, generally does notcarry electrical current between the upper contact portion 154 and thebase, because during operation it is generally not in contact with thebase 150. In general, for all pins implementations disclosed herein,once the pin has been inserted/installed into a pin receiver, the pinwill “flex back” toward an original position to a greater or lesserextent. In other words, there will be some elastic deformation of thepin that will reverse, upon removal of the installation pressure, sothat even if the vertical stop (or the first bend of the N-shape)physically contacts the base during installation, after relaxation, thestops will then no longer contact the base, and so will not electricallycouple the upper contact portion of the pin with the base. Thus, thevertical stops act as mechanical movement restraining elements. TheN-shape of pin 66 is somewhat different in that the first bend 78 alwayscarries current between the upper contact portion 94 and the base 92when current is flowing through the pin 66, but not through the firstbend 78 directly contacting the base—instead the current is carriedbetween the first bend and the base through the slanted section 84,second bend 86, second section 88, and third bend 90.

The pin implementations disclosed herein may be made of any conductivematerials. In general they will be formed of conductive metals, such assteel, copper, nickel, and so forth, and may include conductive and/orprotective coatings (such as corrosion-resistant coatings). Inimplementations each pin is formed from a single contiguous piece ofmetal and is formed through any fabrication technique including forging,stamping, punching, molding, casting, and so forth.

For the pin implementations disclosed herein, the upper contact portionsare configured to mechanically and electrically couple with a pinreceiver. The base of each pin is configured to be soldered to asubstrate to mechanically and electrically couple the pin to asubstrate. For those pins with vertical stops, one or more leg(s) of thepin are configured to flex to allow the bottom contact surface of thevertical stop to move toward the upper contact surface of the base inresponse to a pressure applied to the pin along a direction collinearwith a longest length of the pin toward the upper contact surface of thebase. In implementations, as shown in the drawings, the base is ahorizontal base. The vertical stop in these implementations isconfigured to stop movement of the pin when the bottom contact surfaceof the vertical stop contacts the upper contact surface of the base.

Additionally, with the various pin implementations disclosed herein, thedeformable portion is configured to deform along a directionperpendicular with the longest length of the pin in response toinserting the upper contact portion into the pin receiver. As describedto some extent with respect to the stops 22 and 146, they are configuredto prevent the pin(s) from moving relative to the casing of thesemiconductor package (once the stops contact the casing) when the pinis removed from the pin receiver. In various implementations, the stops22, 146 extend substantially perpendicular to, or perpendicular to, thelongest length of the pin.

The lower portions of pins 2 and 98 are seen to have an s-shape or ashape somewhat resembling an s-shape. As can also be seen, the curvedlegs of pins 2 and 98 are parallel with one another, as are therespective s-shapes.

For each pin described herein, the lower portion may compress when acompressive force is applied to the pin along a direction collinear witha longest length of the pin (such as while pressing the pin into a pinreceiver), and the lower portion may expand when a tensile force isapplied to the pin along a direction collinear with a longest length ofthe pin (such as while removing the pin from a pin receiver).

In places where the description above refers to particularimplementations of flexible press fit pins for semiconductor packagesand related methods and implementing components, sub-components, methodsand sub-methods, it should be readily apparent that a number ofmodifications may be made without departing from the spirit thereof andthat these implementations, implementing components, sub-components,methods and sub-methods may be applied to other flexible press fit pinsfor semiconductor packages and related methods.

What is claimed is:
 1. A pin for a semiconductor package, comprising: anupper contact portion comprising a contact surface configured tomechanically and electrically couple with a pin receiver; a lowerportion comprising a single vertical stop and at least two curved legs;a horizontal base coupled directly to the at least two curved legs andconfigured to be soldered to a substrate to mechanically andelectrically couple the pin to the substrate; and a gap between a bottomcontact surface of the single vertical stop and the upper contactsurface of the horizontal base; wherein the single vertical stop islocated between the at least two curved legs.
 2. The pin of claim 1,wherein the at least two curved legs have an S-shape.
 3. The pin ofclaim 1, wherein the single vertical stop is configured to stop movementof the pin when the bottom contact surface contacts the upper contactsurface.
 4. The pin of claim 1, wherein the upper contact portioncomprises a deformable portion configured to deform along a directionsubstantially perpendicular with the longest length of the pin inresponse to inserting the upper contact portion into the pin receiver.5. The pin of claim 1, wherein the pin comprises a plurality of stopsextending substantially perpendicular to the longest length of the pinand configured to prevent the pin from moving relative to a casing of asemiconductor package when the pin is removed from the pin receiver. 6.The pin of claim 1, wherein a gap is present between the curves of theat least two curved legs.
 7. The pin of claim 1, wherein each of thecurves of the at least two curved legs are substantially parallel.
 8. Apin for a semiconductor package, comprising: an upper contact portioncomprising a contact surface configured to mechanically and electricallycouple with a pin receiver; a lower portion bent into single N-shapecomprising a first section and a second section; a horizontal basecoupled directly to the second section of the lower portion, thehorizontal base configured to be soldered to a substrate to mechanicallyand electrically couple the pin to the substrate, the horizontal basehaving an upper contact surface and the horizontal base extendingsubstantially perpendicularly beyond a width of the upper contactportion; and a gap between a lower contact surface of the first sectionand the horizontal base.
 9. The pin of claim 8, wherein the firstsection of the single N-shape is collinear with the longest length ofthe pin.
 10. The pin of claim 8, wherein the second section of thesingle N-shape is coupled to the horizontal base through a bendcomprising an angle between 60 and 120 degrees.
 11. The pin of claim 8,wherein the single N-shape is configured to flex to allow the lowercontact surface to move toward the upper contact surface in response toa pressure applied to the pin along a direction collinear with a longestlength of the pin toward the upper contact surface.
 12. The pin of claim8, wherein the single N-shape is configured to stop flexing after thesingle N-shape has bent sufficiently to allow the lower contact surfaceto contact the upper contact surface.
 13. The pin of claim 8, whereinthe upper contact portion comprises a deformable portion configured todeform along a direction substantially perpendicular with the longestlength of the pin in response to inserting the upper contact portioninto the pin receiver.
 14. The pin of claim 8, wherein the pin comprisesa plurality of stops extending perpendicularly to the longest length ofthe pin and configured to prevent the pin from moving relative to acasing of a semiconductor package when the pin is removed from the pinreceiver.
 15. A pin for a semiconductor package, comprising: an uppercontact portion comprising a contact surface configured to mechanicallyand electrically couple with a pin receiver; a lower portion comprisinga single vertical stop and at least two curved legs, wherein the atleast two curved legs comprise a first portion and a second portion; ahorizontal base coupled directly to the second portion of the at leasttwo curved legs and configured to be soldered to a substrate tomechanically and electrically couple the pin to the substrate, thehorizontal base having an upper contact surface and the horizontal baseextending substantially perpendicularly beyond a width of the uppercontact portion; and a gap between a bottom contact surface of thesingle vertical stop and the upper contact surface of the horizontalbase; wherein the single vertical stop is located between the at leasttwo curved legs.
 16. The pin of claim 15, wherein the first portion ofeach of the at least two curved legs has a C-shape.
 17. The pin of claim15, wherein the second portion of each of the at least two curved legsis coupled to the horizontal base through a bend comprising an anglebetween 60 and 90 degrees.
 18. The pin of claim 15, wherein the singlevertical stop is configured to stop movement of the pin when the bottomcontact surface contacts the upper contact surface.
 19. The pin of claim15, wherein the upper contact portion comprises a deformable portionconfigured to deform along a direction substantially perpendicular withthe longest length of the pin in response to inserting the upper contactportion into the pin receiver.
 20. The pin of claim 15, wherein the pincomprises a plurality of stops extending perpendicularly to the longestlength of the pin and configured to prevent the pin from moving relativeto a casing of a semiconductor package when the pin is removed from thepin receiver.